FIG. 1 is a perspective view of an exemplary medical injection system 100 (the ACIST CVi® system) adapted to deliver fluids, such as a contrast agent and saline, into a patient's vascular system for medical imaging procedures. FIG. 1 illustrates a first fluid reservoir 132 supplying, via a fill tubing line 27-F, a syringe-type positive displacement pump of a pressurizing unit 130, which is coupled to an injector 140 of system 100; an injection tubing line 27-I is shown coupled to unit 130 for injection of the fluid, for example, a radiopaque contrast agent, into a patient's vascular system via an inserted catheter (not shown), for example, that is coupled to a patient tubing line 122 at a connector 120 thereof. FIG. 1 further illustrates a second fluid reservoir 138 from which saline is drawn by a peristaltic pump 106 through yet another tubing line 128 that feeds into tubing line 122, for injection of the saline into the patient. A manifold valve 124 and associated sensor 114 control the flow of fluids into tubing line 122, from pressurizing unit 130 and from tubing line 128.
FIG. 1 further illustrates a pneumatic user activated control device 200, which is coupled via connectors 251, 253 to an injection control module contained within a control panel 152 of system 100. Control device 200 includes a first compressible bladder 210, which is coupled to, and in fluid communication with a first tubing line 201, and a second compressible bladder 230, which is coupled to, and in fluid communication with a second tubing line 203. Each tubing line 201, 203 is coupled to a corresponding pressure sensor of the injection control module, so that, in response to an external force applied by a user/operator to the corresponding bladder 210, 230, an injection control signal can be generated for the positive displacement pump of pressurizing unit 130 and peristaltic pump 106, respectively, according to the sensed pressure of the corresponding line 201, 203. Control device 200 is preferably calibrated so that an amount of force, above a predetermined threshold, that the operator applies to bladder 210 is proportional to a volume and rate of contrast injected via pressurizing unit 130. Such a control device is described in commonly assigned U.S. Pat. No. 5,916,165. The efficient injection of contrast agent into a patient over the course of an imaging procedure relies on responsive user activated control devices, such as device 200.